Re: [udev] support arguments in callout exec

[Kay Sievers <kay.sievers@vrfy.org>]

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On Thu, Nov 20, 2003 at 01:47:36AM +0100, Arnd Bergmann wrote:
> On Thursday 20 November 2003 13:31, Kay Sievers wrote:
> > +                       for (i=0; i < CALLOUT_MAXARG; i++) {
> > +                               args[i] = strsep(&arg, " ");
> > +                               if (args[i] == NULL)
> > +                                       break;
> > +                       }
> > +                       if (args[i])
> > +                               dbg("to many args");
> 
> This still doesn't look correct: args[i] will be out of bounds
> when the loop has finished on CALLOUT_MAXARG, and the args
> array is not zero terminated when calling execve.
> 
> I haven't tried it yet, but I think this would make more sense:
> 
> +                       for (i=0; i < CALLOUT_MAXARG-1; i++) {
> +                               args[i] = strsep(&arg, " ");
> +                               if (args[i] == NULL)
> +                                       break;
> +                       }
> +			args[i] = arg;
> +                       if (args[i])
> +                               dbg("to many args");

Good catch, but arg is not NULL if MAXARG is reached - so args is still
not terminated :)

Corrected patch attached.

Grüße
Kay


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--- ../udev/namedev.c	2003-11-19 12:56:50.000000000 +0100
+++ namedev.c	2003-11-20 16:41:49.000000000 +0100
@@ -45,6 +45,7 @@
 #define TYPE_TOPOLOGY	"TOPOLOGY"
 #define TYPE_REPLACE	"REPLACE"
 #define TYPE_CALLOUT	"CALLOUT"
+#define CALLOUT_MAXARG	8
 
 static LIST_HEAD(config_device_list);
 
@@ -480,6 +481,9 @@
 	pid_t pid;
 	int value_set = 0;
 	char buffer[256];
+	char *arg;
+	char *args[CALLOUT_MAXARG];
+	int i;
 
 	dbg("callout to %s\n", dev->exec_program);
 	retval = pipe(fds);
@@ -499,7 +503,22 @@
 		 */
 		close(STDOUT_FILENO);
 		dup(fds[1]);	/* dup write side of pipe to STDOUT */
-		retval = execve(dev->exec_program, main_argv, main_envp);
+		if (strchr(dev->exec_program, ' ')) {
+			/* callout with arguments */
+			arg = dev->exec_program;
+			for (i=0; i < CALLOUT_MAXARG; i++) {
+				args[i] = strsep(&arg, " ");
+				if (args[i] == NULL)
+					break;
+			}
+			if (args[i]) {
+				dbg("to many args");
+				args[i] = NULL;
+			}
+			retval = execve(args[0], args, main_envp);
+		} else {
+			retval = execve(dev->exec_program, main_argv, main_envp);
+		}
 		if (retval != 0) {
 			dbg("child execve failed");
 			exit(1);
@@ -528,6 +547,7 @@
 				strncpy(value, buffer, len);
 			}
 		}
+		dbg("callout returned '%s'", value);
 		close(fds[0]);
 		res = wait(&status);
 		if (res < 0) {